@KevinTheJedi
yes, I've updated ubuntu, updated mysql (using mysql_tzinfo_to_sql), checked to make sure that timezones were installed (there are over 1800 in the mysql table), executed the test (CONVERT_TZ) but osTicket still interprets AEST as Melbourne/Australia which is actualy AEDT.
found this Link, but clearing all the session data hasn't fixed the issue.
THIS comment, however has changed it to Australia/Brisbane